unix ExitStatus: Provide .core_dumped

This is essential for proper reporting of child process status on Unix.

Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>

library/std/src/sys/unix/ext/process.rs

@@ -176,6 +176,10 @@ pub trait ExitStatusExt {
     #[stable(feature = "rust1", since = "1.0.0")]
     fn signal(&self) -> Option<i32>;
 
+    /// If the process was terminated by a signal, says whether it dumped core.
+    #[unstable(feature = "unix_process_wait_more", issue = "none")]
+    fn core_dumped(&self) -> bool;
+
     /// Returns the underlying raw `wait` status.
     #[unstable(feature = "unix_process_wait_more", issue = "none")]
     fn into_raw(self) -> i32;
@@ -191,6 +195,10 @@ impl ExitStatusExt for process::ExitStatus {
         self.as_inner().signal()
     }
 
+    fn core_dumped(&self) -> bool {
+        self.as_inner().core_dumped()
+    }
+
     fn into_raw(self) -> i32 {
         self.as_inner().into_raw().into()
     }

library/std/src/sys/unix/process/process_unix.rs

@@ -482,6 +482,10 @@ impl ExitStatus {
         if libc::WIFSIGNALED(self.0) { Some(libc::WTERMSIG(self.0)) } else { None }
     }
 
+    pub fn core_dumped(&self) -> bool {
+        libc::WIFSIGNALED(self.0) && libc::WCOREDUMP(self.0)
+    }
+
     pub fn into_raw(&self) -> c_int {
         self.0
     }